Short Cruise Report MARIA S. MERIAN MSM 43. St. John s Nuuk Chief Scientist: Christian Mertens Captain: Ralf Schmidt

Size: px

Start display at page:

Download "Short Cruise Report MARIA S. MERIAN MSM 43. St. John s Nuuk Chief Scientist: Christian Mertens Captain: Ralf Schmidt"

Carol May
5 years ago
Views:

Dr. Christian Mertens Institut für Umweltphysik Universität Bremen Otto-Hahn-Allee D-28359 Bremen Tel.

1 Dr. Christian Mertens Institut für Umweltphysik Universität Bremen Otto-Hahn-Allee D Bremen Tel.: Fax: Short Cruise Report MARIA S. MERIAN MSM 43 St. John s Nuuk Chief Scientist: Christian Mertens Captain: Ralf Schmidt

2 Objectives The subpolar North Atlantic reacts strongly to the atmospheric forcing and it is expected that global warming will cause significant changes in its large scale circulation and water mass properties. This will lead to changes in heat and freshwater fluxes, which could have consequences for the climate and sea level in western Europe. Studies of recent changes of circulation and water mass properties in the North Atlantic help to understand the processes involved and to separate changes caused by anthropogenic forcing from natural variability. The cruise MSM 43 was dedicated to physical oceanographic observations in the western subpolar North Atlantic by the Institute of Environmental Physics (IUP) at the University of Bremen in collaboration with the Bundesamt für Seeschifffahrt und Hydrographie (BSH) in Hamburg. The work program is part of the joint project RACE! (Regional Atlantic Circulation and Global Change), to study the regional circulation of the Atlantic under global change. It had the following objectives: 1. Investigation of the long-term transport variability of the subpolar gyre and changes of water mass properties of the inflow into the eastern North Atlantic. The transport variability is measured by bottom-mounted inverted echo sounders deployed along a line west of the Mid-Atlantic Ridge. Moored current meters and temperature/salinity recorders along the same line measure the variability of the North Atlantic Current (NAC) and changes of the water mass properties. 2. Estimation of the Labrador Sea Water (LSW) formation rate between 2013 and 2015, and the LSW properties from large scale mapping of the distribution of anthropogenic tracers (SF6 and CFCs). 3. Measurements of the transport of the Deep Western Boundary Current (DWBC) off Newfoundland and Labrador, as well as the export of deep water to the subtropical North Atlantic. Synoptic surveys of current velocity using lowered acoustic Doppler current profilers (LADCP) were carried out along multiple transects across the boundary current. Deployment of two current meter moorings east of Flemish Cap that measure the long-term variability of transport and water mass properties. 4. The outflow of cold deep water in the boundary current is compensated by an inflow of warm water in the NAC. The variability of the NAC and its recirculation in the Newfoundland Basin is measured by inverted echo sounders, that are deployed along 47 N between Flemish Cap and the Mid-Atlantic Ridge. Narrative MARIA S. MERIAN left the port of St. John s, Canada on May 25 at 13:30 (local time) with 15 scientists from the Institute of Environmental Physics (IUP) at the University of Bremen, 2 scientists from the Bundesamt für Seeschifffahrt und Hydrographie (BSH) in Hamburg, and one guest scientist from the University of Alberta, Canada. Underway measurements (shipboard ADCPs, thermosalinograph, multibeam echo sounder) were started shortly after leaving the three-mile zone, at about 15:00 (local time). On May 26 a test of the CTD/rosette was made, by lowering the CTD to a depth of 100 m and closing all bottles. The first working area east of Flemish Cap was reached on May 27, where data recorded by a bottom-mounted inverted echo sounder (PIES) during the past year were retrieved acoustically using the ships hydrophone. Afterwards we proceeded to the current meter mooring B22 that was successfully released and completely recovered. After a transit to the northern edge of Flemish Cap we started our first CTD/LADCP section (stations 213 to 237) toward Cape Farewell at the southern tip of Greenland. The first part of this section was in northwest direction (crossing the DWBC perpendicular to the slope), the later part followed straight north along W. On station 214 we experienced noisy

3 conductivity data below a depth of about 500 m. For the next station we switched to the second winch (EL1), but the problem remained and we switched back to winch EL2. The problem was difficult to locate, as it occurred only at a pressure above 500 dbar, we therefore used the ships CTD/rosette systems for stations 215 and 216 and returned to our own CTD on station 217, after having changed a number of cables and sensors. The CTD worked mostly flawless thereafter. On May 30 the station work had to be stopped after station 226, due to the weather conditions (wind about 20 m/s). The ship was rolling heavily and CTD work was no longer possible. For the next 18 hours we moved north along the track without CTD stations. The station work was resumed in the morning of May 31 (station 227), but was again interrupted in the morning of June 1 (after station 231), due to the weather now with wind of about 25 m/s. The CTD work was continued in the early morning of June 2 and the section completed in the afternoon of the same day (station 237). At Cape Farewell we started the next CTD/LADCP section in southeastward direction across the Irminger Sea and then along the western flank of the Mid-Atlantic Ridge (stations 237 to 271). On June 5 we arrived at the northern end of our mooring array along the Mid-Atlantic Ridge, that consisted of four moorings with currents meters and temperature/conductivity recorders and three bottom-mounted PIES. Moorings and PIES are aligned the Charlie-Gibbs, Faraday, and Maxwell Fracture Zones to measure the variability of volume transport and water mass properties of the NAC as it crosses the Mid- Atlantic Ridge into the eastern basin of the North Atlantic. Servicing of the array was started by data retrieval at PIES BP15 by acoustic telemetry. Afterwards the mooring GFZ was released and all instruments recovered. We then proceeded southeastward along the array and arrived at PIES BP14 in the evening. The PIES data were retrieved acoustically and afterwards the instrument was released and then recovered. In the morning of June 6 the nearby mooring FFZ-1 was released and fully recovered. The instruments from the moorings GFZ and FFZ-1 were serviced on board, while CTD work was done along the section until we eventually returned to the GFZ position and re-deployed the mooring on June 8. After a transit back southeastward we arrived at mooring FFZ-2 in the morning of June 9. Release and Pinger-On commands where send but no response from the acoustic releases was received. We tried two different deckunits and two different hydrophones, that all worked flawless during the previous mooring operations, without success. The procedure was repeated at four different positions around the expected mooring position but no response from the releases was received. After three hours, and an attempt to identify mooring elements using the water column mode of the multibeam echo sounder, we left the station and resumed the CTD work southeastward along the section. We then reached the fourth mooring of the array (MFZ) in the afternoon of June 10, but again had no success in recovering the mooring. This time response was received from both acoustic releases but they did not rise from the seafloor. Diagnostic commands where send to the releases and the response indicated that they where probably still vertical and not lying flat on the seafloor. As it was already in the afternoon we decided to wait for the next morning and then dredge for the mooring. During the night we moved to PIES BP12, retrieved the data acoustically and then released the instrument. After the recovery a serviced instrument (previously at position BP14) was deployed and surveyed. We returned to the position of mooring MFZ in the morning of June 11 and again tried to send commands to the releases. This time we no longer received any response. Therefore we had to assume that the releases had unhooked and that the mooring surfaced during the night. We started a four-hour search in eastward direction (downstream of the prevailing current), but despite the calm sea and excellent visibility no remnants of the mooring could be found.

4 Further no signals were received from the radio transmitter of the mooring. After noon we returned to the expected mooring position and started dredging which lasted until late in the evening but without any success. Again we have to assume that the mooring is lost. In addition to the CTD and mooring work, three ARGO floats were deployed along the Mid- Atlantic-Ridge, at the positions of moorings GFZ, FFZ-1, and MFZ. In the morning of June 12 we started the CTD section along 47 N. On June 13 a float was deployed early in the morning (station 278) and in the afternoon we arrived at PIES BP30 to retrieved its data by acoustic telemetry. The data of next PIES (BP29) were retrieved in the morning of June 14. During that day the wind speed increased continuously to m/s when we arrived at PIES BP28. Because the ships pump-jet was needed to hold the position, it was no longer possible to use the ships build-in hydrophone for telemetry. Instead an external hydrophone was mounted to a 350 kg dummy weight and then lowered over the side. After the data retrieval the station work had to be interrupted due to the weather conditions, except for a float deployment (station 285) in the afternoon of June 15. The CTD work was then resumed in the evening of the same day (station 286). The last PIES station (BP27) was reached in the morning of June 16 and the data were again retrieved using the hydrophone over the side. The CTD section was then continued toward the continental slope off Flemish Cap, where two current meter moorings were deployed on June 17, B24 in the morning and B22 in the afternoon. After the mooring deployments the CTD work along 47 N was completed early in the morning of June 18 (station 300). A transit of 360 nautical miles brought us to the next CTD section that was started in the morning of June 20 in the southeastern Labrador Sea (station 299). The section headed in northwest direction toward the central Labrador Sea and was finished in the evening of June 21 (station 304). From there on we proceeded southwest to the continental slope on the Canadian side of the Labrador Sea where we started CTD stations along the so-called AR7W section on June 21. This former WOCE line crosses the central Labrador Sea from Hamilton Bank on the Canadian Shelf to Cape Desolation at the west coast of Greenland. The last station (326) on the Greenland shelf was reached in the evening of June 25. This was the last CTD cast of the cruise MSM 43, and also the recoding of bathymetry and shipboard ADCP data was stopped after that station. Other underway data were recorded until June 26, 16:00 local time. On June 27 MARIA S. MERIAN arrived in the port of Nuuk at 10:00 local time. Acknowledgements We thank Captain Ralf Schmidt and the entire crew of MARIA S. MERIAN for the friendly and cooperative atmosphere and their professional technical assistance. We are grateful to the Canadian and Danish authorities for the permission to conduct scientific research in the exclusive economic zones of Canada and Greenland. The Control Station German Research Vessels (Leitstelle Deutsche Forschungsschiffe), Klaus Bohn (LPL Projects + Logistics GmbH), and Barbara Kozak (University of Bremen) provided logistical and administrative support. Financial support came from the German Ministry of Education and Research (BMBF) as part of the joint project RACE! (Regional Atlantic Circulation and Global Change) and the Deutsche Forschungsgemeinschaft (DFG).

5 Scientific Personnel 1. Mertens, Christian Chief Scientist IUPHB 2. Böke, Wolfgang Technician IUPHB 3. Köhler, Janna lowered ADCP IUPHB 4. Roessler, Achim PIES, shipboard ADCP IUPHB 5. Steinfeldt, Reiner Hydrography IUPHB 6. Castro de la Guardia, Laura Oxygen sampling UALB 7. Bulsiewicz, Klaus Tracer IUPHB 8. Christodoulou, Aliki Tracer IUPHB 9. Zeiss, Marie Tracer IUPHB 10. Schneehorst, Anja Moorings BSH 11. Uhde, Hans Hermann Moorings BSH 12. Stake, Jürgen Moorings IUPHB 13. Cordts, Robert CTD IUPHB 14. Kappertz, Lars CTD IUPHB 15. Nüß, Rasmus CTD IUPHB 16. Sonntag, Isabelle CTD IUPHB 17. Spanknebel, Martin CTD IUPHB 18. Wegehaupt, Timm CTD IUPHB IUPHB Institut für Umweltphysik Universität Bremen Otto-Hahn-Allee Bremen / Germany BSH Bundesamt für Seeschifffahrt und Hydrographie Bernhard-Nocht-Str Hamburg / Germany UALB University of Alberta Department of Earth and Atmospheric Sciences 1-26 Earth Sciences Building Edmonton, Alberta T6G 2E3 / Canada

6 List of PIES stations Station Site PIES S/N Date Latitude Longitude Depth (m) Action MSM43/211-1 BP /05/27 03:16 06: 'N 'W 4236 Telemetry MSM43/249-1 BP /06/05 05:53 09: 'N 'W 3386 Telemetry MSM43/251-1 BP /06/05 23:19 02: 'N 'W 3631 Telemetry MSM43/251-2 BP /06/06 02:53 04: 'N 'W 3631 Recovery MSM43/271-1 BP /06/10 22:53 03: 'N 'W 4091 Telemetry MSM43/271-1 BP /06/11 03:18 04: 'N 'W 4091 Recovery MSM43/271-2 BP /06/11 05:00 07: 'N 'W 4090 Deployment MSM43/280-1 BP /06/13 16:12 19: 'N 'W 4546 Telemetry MSM43/282-2 BP /06/14 08:24 11: 'N 'W 4607 Telemetry MSM43/284-2 BP /06/15 01:12 04: 'N 'W 4578 Telemetry MSM43/287-2 BP /06/16 05:21 08: 'N 'W 4486 Telemetry List of mooring recoveries Station Site Date Latitude Longitude Depth (m) MSM43/212-1 B /05/27 10:05 12: N W 3000 MSM43/250-1 GFZ 2015/06/05 09:54 13: N W 3610 MSM43/252-1 FFZ /06/06 09:52 13: N W 4310 List of mooring deployments Station Site Date Latitude Longitude Depth (m) MSM43/262-1 GFZ 2015/06/08 14:05 17: N W 3610 MSM43/293-1 B /06/17 11:04 12: N W 4000 MSM43/294-1 B /06/17 17:26 19: N W 3000 List of float deployments Station Float S/N Date Latitude Longitude WMO ID Iridium ID MSM43/ /06/05 15: N W MSM43/ /06/60 16: N W MSM43/ /06/09 17: N W MSM43/ /06/13 07: N W MSM43/ /06/15 15: N W

7 List of CTD/LADCP stations Station CTD Cast Date Latitude Longitude Depth (m) SF6 & CFC He Comment MSM43/ /05/27 23: 'N 'W 552 x - MSM43/ /05/28 01: 'N 'W 763 x - bad data below 530 dbar MSM43/ /05/28 03: 'N 'W cast aborted at 555 dbar MSM43/ /05/28 05: 'N 'W bad data below 645 dbar MSM43/ /05/28 07: 'N 'W no LADCP MSM43/ /05/28 10: 'N 'W 1590 x - no LADCP MSM43/ /05/28 13: 'N 'W 2169 x - MSM43/ /05/28 15: 'N 'W 2807 x - MSM43/ /05/28 18: 'N 'W 3377 x - MSM43/ /05/28 21: 'N 'W 3892 x - MSM43/ /05/29 01: 'N 'W MSM43/ /05/29 06: 'N 'W 4368 x - MSM43/ /05/29 11: 'N 'W 4230 x - bad data on upcast MSM43/ /05/29 16: 'N 'W 4324 x - MSM43/ /05/29 23: 'N 'W 4175 x - MSM43/ /05/30 06: 'N 'W 4153 x - MSM43/ /05/31 09: 'N 'W 3513 x x MSM43/ /05/31 15: 'N 'W 3428 x x MSM43/ /05/31 21: 'N 'W 3436 x x MSM43/ /06/01 02: 'N 'W 3183 x x MSM43/ /06/01 06: 'N 'W 2390 x x MSM43/ /06/02 04: 'N 'W 1660 x x MSM43/ /06/02 08: 'N 'W 1683 x x MSM43/ /06/02 10: 'N 'W 1770 x x MSM43/ /06/02 13: 'N 'W 1208 x x MSM43/ /06/02 14: 'N 'W 311 x x MSM43/ /06/02 15: 'N 'W 244 x x MSM43/ /06/02 19: 'N 'W 1700 x - MSM43/ /06/02 23: 'N 'W 2615 x - MSM43/ /06/03 03: 'N 'W 3178 x - MSM43/ /06/03 09: 'N 'W 3125 x - MSM43/ /06/03 14: 'N 'W 3012 x - MSM43/ /06/03 20: 'N 'W 3442 x - MSM43/ /06/04 01: 'N 'W 3374 x - MSM43/ /06/04 07: 'N 'W 2908 x - MSM43/ /06/04 13: 'N 'W 2773 x - MSM43/ /06/04 18: 'N 'W 3029 x - MSM43/ /06/04 22: 'N 'W 3753 x - MSM43/ /06/05 03: 'N 'W 3387 x - MSM43/ /06/05 13: 'N 'W MSM43/ /06/06 04: 'N 'W 3609 x x 39 Ar & 3 H samples MSM43/ /06/06 13: 'N 'W MSM43/ /06/06 18: 'N 'W 3921 x - MSM43/ /06/06 22: 'N 'W 3905 x - MSM43/ /06/07 03: 'N 'W 4211 x - MSM43/ /06/07 12: 'N 'W 4013 x - MSM43/ /06/07 16: 'N 'W 3837 x - instrument calibration MSM43/ /06/07 21: 'N 'W 3552 x - MSM43/ /06/08 02: 'N 'W 3879 x - MSM43/ /06/08 06: 'N 'W 3712 x - MSM43/ /06/08 10: 'N 'W 3410 x - MSM43/ /06/09 15: 'N 'W 3936 x - MSM43/ /06/09 20: 'N 'W 4078 x - MSM43/ /06/10 00: 'N 'W 4014 x - MSM43/ /06/10 05: 'N 'W 3626 x - MSM43/ /06/10 09: 'N 'W 3926 x - MSM43/ /06/10 18: 'N 'W 3788 x - MSM43/ /06/11 05: 'N 'W 4080 x - MSM43/ /06/12 03: 'N 'W 3741 x - MSM43/ /06/12 07: 'N 'W 3831 x - MSM43/ /06/12 12: 'N 'W 4070 x - MSM43/ /06/12 18: 'N 'W 4268 x -

8 MSM43/ /06/12 23: 'N 'W 4222 x - MSM43/ /06/13 04: 'N 'W 4326 x - MSM43/ /06/13 10: 'N 'W 4450 x - MSM43/ /06/13 16: 'N 'W 4553 x x 39 Ar & 3 H samples MSM43/ /06/13 22: 'N 'W 4590 x - instrument calibration MSM43/ /06/14 05: 'N 'W 4616 x - MSM43/ /06/14 14: 'N 'W 4589 x - MSM43/ /06/14 21: 'N 'W 4584 x - MSM43/ /06/15 20: 'N 'W 4571 x - MSM43/ /06/16 02: 'N 'W 4512 x - MSM43/ /06/16 11: 'N 'W 4351 x - MSM43/ /06/16 16: 'N 'W 4264 x - MSM43/ /06/16 20: 'N 'W 3995 x - MSM43/ /06/17 00: 'N 'W 3650 x - MSM43/ /06/17 04: 'N 'W 3522 x - MSM43/ /06/17 20: 'N 'W 3307 x - MSM43/ /06/17 23: 'N 'W 1923 x - MSM43/ /06/18 01: 'N 'W 1159 x - MSM43/ /06/18 04: 'N 'W 558 x - MSM43/ /06/20 04: 'N 'W 3973 x - MSM43/ /06/20 12: 'N 'W 3764 x - MSM43/ /06/20 20: 'N 'W 3637 x - MSM43/ /06/21 04: 'N 'W 3761 x - MSM43/ /06/21 12: 'N 'W 3686 x - MSM43/ /06/21 20: 'N 'W 3638 x x 39 Ar & 3 H samples MSM43/ /06/22 02: 'N 'W 3461 x - MSM43/ /06/22 14: 'N 'W 450 x - MSM43/ /06/22 15: 'N 'W 887 x - MSM43/ /06/22 17: 'N 'W 1775 x - MSM43/ /06/22 19: 'N 'W 2454 x - MSM43/ /06/22 22: 'N 'W 2971 x - MSM43/ /06/23 02: 'N 'W 3043 x - MSM43/ /06/23 07: N 'W 3322 x - MSM43/ /06/23 12: 'N 'W 3550 x - MSM43/ /06/23 16: 'N 'W 3541 x - MSM43/ /06/23 21: 'N 'W 3540 x x MSM43/ /06/24 04: 'N 'W 3518 x x MSM43/ /06/24 10: 'N 'W 3574 x x MSM43/ /06/24 16: 'N 'W 3527 x x 3 H samples MSM43/ /06/24 22: 'N 'W 3457 x x 3 H samples MSM43/ /06/25 04: 'N 'W 3370 x x MSM43/ /06/25 10: 'N 'W 2959 x x MSM43/ /06/25 13: 'N 'W 2819 x x CFC offline samples MSM43/ /06/25 16: 'N 'W 1762 x x CFC offline samples MSM43/ /06/25 17: 'N 'W 774 x x CFC offline samples MSM43/ /06/25 19: 'N 'W 186 x x CFC offline samples MSM43/ /06/25 19: 'N 'W x

Short Cruise Report - RV Meteor, cruise M85/1 Brest St. John's

Short Cruise Report - RV Meteor, cruise M85/1 Brest St. John's Short Cruise Report, RV Meteor, cruise M85, leg 1, Brest-St. John's, Jun 24th Aug 2nd 2011 Dr. Dagmar Kieke Institut für Umweltphysik AG Ozeanographie Universität Bremen Otto-Hahn-Allee D-28359 Bremen